1. Field of Invention
This invention relates to civionics and, in particular, to a method and apparatus for differential voltage grid-based moisture monitoring of structures.
2. Description of Related Art
A conventional low-sloped roof includes a roof deck, such as may be made of concrete or similar building material, a water impermeable membrane assembly on top of the roof deck, and optionally overburden, such as may be formed of aggregate material, laid on top of the membrane assembly.
Some conventional roofs include a grid of longitudinally and laterally disposed electrically conductive wires or tape which are electrically insulated from each other. The grid is installed above the membrane assembly and beneath the overburden, for the purpose of detecting moisture ingress into the building structure through defects in the membrane assembly. Such moisture ingress detection relies on the moisture present on the roof including elemental ions which create a detectable electrical current when the ions flow through a defect.
Canadian patent No. 2,599,087 issued to Vokey discloses a method of locating a defect in a roof comprising generating an applied voltage having a positive attached to the roof deck and a negative attached to at least one of the grid wires, and sensing at each of the wires in turn the electrical current flowing through the wire being sensed in response to the applied voltage. However, the method of Vokey relies on a measurement of electrical current through a grid wire rather than a measurement of the electrical current flow of the elemental ions flowing within moisture present on the roof.
An object of the invention is to address the above shortcomings.